Introduction: Hekla volcano, Iceland

Iceland's most
famous and historically most active volcano can best be described as an intermediate volcanic form
between a crater row and a stratovolcano. It is located west of Iceland's
SE volcanic rift-zone. Hekla erupts a magma type that
is unique for Iceland, intermediate between highly silicic and andesitic
composition. From surface deformation studies after the 1980 eruption, it
has been concluded that its magma chamber is located around 8 km below the
summit. Since the Middle Ages, Hekla's has been one of the most active
volcanoes of the world, with recorded major eruptions in 1104, 1158, 1206, 1222,
1300, 1341, 1389, 1510, 1597, 1636, 1693, 1766, 1845, 1947, 1970, 1980,
1991 and 2000. Typically, at least the
beginning parts of Hekla's eruptions are largely explosive. Some of these eruptions
caused great damage, especially the eruptions in 1510, 1693 and 1766. Note
that since 1970 the repose interval appears to have changed, becoming much
shorter and quite regular, around 10 years, with respect to an
approximately 50 years rhythm during the preceding centuries. Hekla
has also had a number of large prehistoric but postglacial eruptions, producing vast amounts of
tephra which repeatedly covered up to two thirds of the country with
light-coloured tephra (i.e. 7000 B.P., 4500 B.P., 2900 B.P., A.D. 1104 and
A.D. 1158). The
total volume of lava produced by Hekla in historical times is about 8 km3,
and the total volume of tephra about 7 km3.

8 March 2000
As reported by NORDVULC,
the
eruption is now considered to be over. The last weak volcanic activity
occurred on 5 March, and the last tremor signal on 8 March. The eruption
emplaced about 0.11 km3 of lava, mostly as flows covering an area of
about 18 km2.

1 March 2000
As reported by the newspaper Morgunblašiš,
the eruption has again increased in intensity. This time, ash was transported
westwards and fell on Rejkjavik but did not cause damage. The area covered by
lava flows is now estimated to be 16-18 km2.

27 February 2000
In the evening of February 27 the main lava flow from the
eruptive fissure was slowly advancing at a rate of some meters per hour. A more
active lava stream emanates from three craters near the southern end of the
eruptive fissure. On February 27 this lava stream was several km long and was
advancing at a rate of about a meter per minute.

26 February 2000
Hekla volcano in South Iceland erupted after a repose interval of just 9 years on February 26, 2000 at 18:19 GMT. Initially, a 6-7 km long eruptive fissure opened up along most of the Hekla
ridge. A discontinuous curtain of fire emanated from the whole fissure. A more
than 10 km high ash plume formed within few minutes of the explosive beginning of the
eruption. The ash was carried with light winds towards north and most of it fell
in uninhabited areas in the interior of Iceland, but a small amount of ash fell
in inhabited areas in North Iceland.
After the first hour the activity gradually declined and soon became
predominantly effusive.